This section introduces aspects that may help facilitate a better understanding of the invention. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
The marriage of wireless communication services and location based services has been observed. For example, in the United States, the “E911” mandate requires that a wireless service provider automatically obtain information concerning a location of a wireless caller calling for emergency help, i.e., without the caller having to provide the location information, and route the call to the appropriate emergency responder for the caller's location. Such E911 service is important in times of fires, break-ins, kidnapping, and other events where communicating one's location is difficult or impossible. To facilitate the E911 service, more and more mobile devices (e.g., mobile phones) have been “global positioning system (GPS) enabled” by incorporating therein a GPS receiver for receiving signals from GPS satellites to determine the devices' location.
However, a GPS enabled mobile device when used indoors or other non-optimal settings, where the line of sight to the GPS satellites is obstructed or interfered, oftentimes cannot effectively provide GPS information concerning its location. To help a mobile device with effective location acquisition, especially on power up of the mobile device, a well known assisted GPS (A-GPS) service has been deployed by wireless service providers which, for example, may supply through a data channel to the mobile device orbital, clock and other data about the GPS satellites relevant to the mobile device. The wireless service providers have base stations installed therein GPS receivers receiving signals from the GPS satellites. Based on the received satellite signals, the orbital, clock and other data, including GPS information about a base station's own location, can be computed. A base station may pass the computed information to the mobile devices served thereby to realize the A-GPS.
Many location based services involving mobile devices have emerged since the E911 initiative, which include, for instance, a chaperon service whereby a parent may be informed of a location of a child carrying a mobile device, e.g., whether the child has exited or entered a geographic area previously defined by the parent. Recently, the ability of a mobile device to provide GPS location information fueled proliferation of such location based services as targeted advertising, and customized traffic, map, weather and other services based on the current location of the device. Wireless service providers would also benefit from the location information from mobile devices using their services, e.g., to dynamically optimize their network capacity to better serve wireless customers in crowded areas.